Written by Tabish Mehraj, PhD, Science Writer. This study evaluated the effects of blueberry consumption, which may upregulate the ability of the geriatric human gut to use dietary polyphenols by changing the fecal microbiome. It led to the reductions in HDL and APoA-I. These findings suggest that blueberries target specific beneficial gut bacteria, offering unique advantages when combined with exercise, but their overall metabolic impact warrants further investigation.

The gut microbiome is the massive community of bacteria in our digestive system and is increasingly known as a significant determinant of human health which influences mental well-being and overall physical and cardiovascular health. As we age, maintaining a healthy, diverse microbiome becomes even more challenging and crucial, especially for the people who are managing obesity or being overweight, conditions that are often linked to an altered gut microbiome. A recent promising study known as the BEACTIVE Trial, which was published in Nutrients (2025), analyzed whether consistent high level, everyday blueberry consumption could potentially benefit or modify the gut environment in a sedentary geriatric population with obesity (BMI 25–32 kg/m²).

This 12-week randomized, double-blinded, placebo-controlled pilot study conducted by researchers at Duke University investigated the impact of regular blueberry consumption on the fecal microbiome and cardiometabolic biomarkers. Participants (n=55) were randomized to daily consumption of either lyophilized blueberry powder (equivalent to 1.5 cups of blueberries, providing 1116 mg phenolic and 382 mg anthocyanins) or an indistinguishable placebo. Both groups participated in weekly supervised exercise and were encouraged to increase daily step counts. The placebo group consumed a powder without blueberry content as a control. Both groups were supervised with respect to their physical exercise and daily step count. Scientific assessment involving advanced technologies such as 16S rRNA gene sequencing, profiled bacterial communities within fecal samples, providing a detailed snapshot of the gut microbiome. Nuclear Magnetic Resonance (NMR) spectroscopy measured various circulating metabolites and cardiovascular health markers in blood samples, offering insights into whether systemic physiological changes were employed.

Key Findings/ Results:

• Fecal Microbiome Modulation: The most interesting and significant finding was the enrichment of Coriobacteriales incertae sedis in the fecal microbiome of the blueberry group (p = 0.049), which increased in 70.6% of participants. This taxonomic group is known to facilitate the metabolism of dietary polyphenols. This enrichment suggests that regular blueberry intake may upregulate the gut’s capacity to process bioactive compounds like anthocyanins.

• Cardiometabolic and Lipid Profiles: The results regarding circulating biomarkers were complex. The placebo group saw significant reductions in total cholesterol (−9.2 mg/dL, p = 0.019), LDL-C (−9.2 mg/dL, p = 0.008), and ApoB (−5.5 mg/dL, p = 0.016), while the blueberry group experienced significant decreases in total HDL-P (−1.1 μmol/L, p = 0.021) and ApoA-I (−8.5 mg/dL, p = 0.010). Correlation analysis in the blueberry group revealed a strong negative relationship between the increase in Coriobacteriales and large LDL particles (ρ = −0.763, p = 0.002). The blueberry group did not show these broad improvements, instead exhibiting significant reductions in total HDL particles (HDL-P) (p = 0.021) and apolipoprotein A-I (ApoA-I) (p = 0.010).

• Gut-Related Metabolites: The study examined metabolites like trimethylamine-N-oxide (TMAO), betaine, and choline. The placebo group had a significant increase in fasting TMAO (+0.6 μM, p = 0.014), whereas the blueberry group showed a non-significant downward trend from a baseline of 1.9 μM. These results highlight that, while blueberries specifically target certain bacterial populations, their broader metabolic effects in this population are complex and distinct from exercise alone.

The BEACTIVE trial provides pilot data suggesting that regular blueberry consumption can specifically enrich gut bacteria involved in polyphenol metabolism in an older, sedentary population. However, the lack of broad improvements in cardiometabolic markers—and the unexpected improvements in the placebo group—highlights the complexity of nutritional interventions. The study underscores the need for larger, longer-term trials to determine if these microbiome changes eventually translate into meaningful clinical benefits for cardiovascular health.

One of the major strengths of the study is its randomized controlled design. Furthermore, the study targeted geriatric population which addressed a gap in the literature. The 12-week follow-up period also allowed for observation of both short- and intermediate-term effects of blueberry supplementation. This was a pilot study with a relatively small number of participants (only 38 in the final microbiome analysis). The results are statistically strong for this but furthermore studies across much diverse populations are required to confirm broader applicability. The 12-week trial was sufficient to spot changes in some metabolites and specific gut bacteria. However, it was relatively concise to produce significant changes in overall cholesterol levels. Longer-term studies are necessary to assess sustained effects and impacts on chronic disease risk. Not all participants showed the same response; approximately 70% of the blueberry group experienced an increase in beneficial Coriobacteriales incertae sedis. This highlights that unique baseline microbiomes, genetic predispositions, and other lifestyle factors mean a “one-size-fits-all” approach may not apply. Individual responses can vary. Blueberry intake, therefore, should be best viewed as a supportive element within an overall healthy lifestyle.

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Posted April 15, 2026.

Dr. Tabish Mehraj is a pharmaceutical scientist with expertise in pharmaceutics, drug delivery, and formulation development. She earned her PhD in Pharmaceutical Sciences from the University of Mississippi, where her research focused on the formulation, optimization, and characterization of lipid-based nanocarriers for targeted liver delivery of antimalarial therapeutics. Dr. Mehraj has also served as an ORISE Fellow at the U.S. Food and Drug Administration (FDA), where she evaluated the effects of formulation and process design on the quality and performance of intravaginal drug delivery systems and developed bio-relevant in vitro drug release testing methods. She has teaching experience in pharmaceutical and life sciences courses and has authored peer-reviewed publications, book chapters, and conference presentations. Dr. Mehraj is an active member of the American Association of Pharmaceutical Scientists and has been recognized by honor societies including Rho Chi and Gamma Beta Phi. 

References: 

1. Porter Starr, K. N., Connelly, M. A., Wallis, J., North, R., Zhang, Q., Song, K., … & Bales, C. W. (2025). Effects of blueberry consumption on fecal microbiome composition and circulating metabolites, lipids, and lipoproteins in a randomized controlled trial of older adults with overweight or obesity: The BEACTIVE trial. Nutrients, 17(7), 1200.